On Wed, Jul 15, 2009 at 11:17 AM, Johannes
Berg<johannes@xxxxxxxxxxxxxxxx> wrote:
> On Wed, 2009-07-15 at 11:02 -0700, Andrey Yurovsky wrote:
>> mesh_path_add allocates an mpath and a node but it is called with RCU
>> held. Use the GFP_ATOMIC flag to prevent these allocations from
>> sleeping since otherwise we can hit the following sleep-while-atomic:
>
> This isn't sufficient, quoting from the function, highlight added:
>
> int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata)
> {
> ...
> if (grow) {
> struct mesh_table *oldtbl, *newtbl;
>
> write_lock(&pathtbl_resize_lock);
> oldtbl = mesh_paths;
> newtbl = mesh_table_grow(mesh_paths);
> if (!newtbl) {
> write_unlock(&pathtbl_resize_lock);
> return 0;
> }
> rcu_assign_pointer(mesh_paths, newtbl);
> write_unlock(&pathtbl_resize_lock);
>
> ******* synchronize_rcu();
> mesh_table_free(oldtbl, false);
> }
> ...
> }
>
> johannes
>
Yes, we'll address growing the issue separately. Ok, we'll send a new
patch for the allocations as well as growing the table in the future.
-Andrey
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